Manufacture of heat exchange tubing



Dec. 8, 1964 MANUFACTURE OF HE Original Filed Aug. 26, 1960 H. J. VENABLES Ill AT EXCHANGE TUBING 4 Sheets-Sheet l INVENTOR.

HERBERT I \VENABLES 111 HlS ATTORNEY Dec. 8, 1964 H. J. VENABLES m 3,160,129

MANUFACTURE OF HEAT EXCHANGE TUBING Criginal Filed Aug. 26, 1960 4 Sheets-Sheet 2 FIG.2

INVENTOR. HERBERT J. VENABLES m HIS ATTORNEY Dec. 8, 1964 H. .1. VENABLES m MANUFACTURE OF HEAT EXCHANGE TUBING 4 Sheets-Sheet 3 Criginal Filed Aug. 26, 1960 IN VEN TOR. ERBERT I VENABLES I11 H15 ATTORNEY Dec. 8, 1964 H. J. VENABLES m 3,

MANUFACTURE OF HEAT EXCHANGE TUBING Criginal Filed Aug. 26, 1960 4 Sheets-Sheet 4 u 2 16.9 FIG.& 82

l 1|ll"lllllllllllilllilllllllil In -lll INVENTOR.

HERBERT 3'. VENABLES In:

H\S ATTORNEY United States Patent 3,160,129 MANUFAQTURE ill HEAT EXQHANGE TUllTNG Herbert J. Venables Til, Qleveland, tl hio, assignor to General Electric Qorn'pany, a corporation of New York @riginal application Aug. 26, 19649, Ser. No. 52,252, new Eatent No. 3,134,156, dated May as, 1964. Divided and this application .ian. ltd, 1963, der. No. 25$,llfi? Qlaims. till. 1l3--1) The present invention relates to the manufacture of finned tubing employed for heat exchange purposes and has at its principal object the provision of an improved machinery for producing finned tubing having a multitude of slender tin sections extendingoutward in radiating fashion from the tubing. This application is a division of my copending application Serial No. 52,252, filed August 26, 1960, now Patent No. 3,134,166, and is assigned to the General Electric Company, the assignee of said application Serial No. 52,252.

The present invention is an improvement over the invention of my previous application S.N. 763,514, filed September 26, 1958, now Patent No. 3,065,253, dated October 24-, 1961, and assigned to the assignee of the present invention, which invention was made by me prior to the present invention. 1, therefore, do not herein claim anything shown or described in the previous application, which is to be regarded as prior art with respect to this present application.

The machine of the present invention comprises a rotatable head mounted for rotation in a base member. The head carries a coil supporting table around the periphery thereof which is rotatable with respect to the head. A hollow spindle extends upwardly through an axial passage in the head and is mounted for rotation independently from but in timed relation with the rotation of the head and at a rotational velocity diliering from that ofthe rotatable head. The hollow spindle carries a sun gear for driving gear means in the rotatable head which, in turn, advance the coil supporting table around the rotatable head a predetermined amount for each revolution of the head. Also driven in timed relation with the rotation of the head by the gear means on the head is a slitting means which acquires strip stock from the coil supporting table and slits the stock at intervals inwardly from both edges thereof toward the center to form a plurality of slender fin sections each connecting at their inner ends with a base section extending the length of the strip. After slitting, the strip stock is directed between a pair of forming rolls, including a grooved roll on the upper end of the spindle and a backing roll journalled in the head. The backing roll forces the base section of the strip into the grooved roll and forms the strip into a substantially U-shaped cross section with narrow portions of the base section on both sides thereof being formed at approximately a right angle with respect to the remaining portions of the base section. A hem forming means is mounted on the head and driven in timed relation with the rotation of the head. The hem forming means includes a grooved roll for receiving the base section of the U-shaped strip, a backing roll extending into the opening or" the U-shaped strip, and a pair of diagonal rolls adapted to engage the narrow portions of the base section and bend them inwardly upon the remaining portion of the base section while the backing roll retains the fin sections on either side thereof extending outwardly at approximately a right angle with respect to the base section. l/leans are also provided in the base for advancing a tubular member through the hollow spindle at a programmed rate and into the head wherein the formed fin strip is wrapped thereon in helical fashion as the head is rotated about the tubing.

' arrears Ce Patented Dec. 8, 1964 For a better understanding of the invention, reference may be had to the'accompanying drawings in which:

FIG. 1 is an elevational view of the machine of the present invention with portions of the machine broken away;

FIG. 2 is a plan view of the rotatable wrapping head looking down upon the head from the top;

PEG. 3 is a cross sectional view taken substantially along line 3-3 of FIG. 1 showing the gearing arrangement for driving the various components in the rotatable head;

FIG. 4 is a cross sectional view taken approximately along line 4-4 of FIG. 1 showing the gear arrangement for independently driving the rotatable head and the hollow spindle extending upwardly into the head;

FIG. 5 is a cross sectional view taken substantially along line 55 of H6. 2 illustrating the grooved forming roll on the upper end of the spindle and mating backing roll on the head for bending the fin strip into a substantially U-shaped cross section;

FIG. 6 is an enlarged view of the forming rolls of FIG. 5 showing the in! strip being formed into a substantially U-shaped cross section;

FIG. 7 is a cross sectional view taken substantially along line 7-7 of FIG. 2 showing the fin slitting rolls and the gearing means on the head for driving the slitting rolls;

FIG. 8 is a cross sectional view taken approximately along line 38 of FIG. 2 illustrating the hem forming rolls and the gear drive in the rotatable head for operating these hcmming rolls;

FIG. 9 is an enlarged detail view of the hemming rolls showing the bending operation wherein the narrow portions of the base section are reversely bent upon the base section to form the double thickness hem or edge portion on opposite sides of the base section;

FIG. 10 is a detailed view of one side of the slitting rolls illustrating their slitting operation;

IG. 11 is a view of a section of the strip stock after it has passed through the slitting rolls illustrating the fin sections on both sides of the strip all connecting with a center or base section extending the length of the strip; and

FIG. 12 is a cross sectional view of the finned tube showing the manner in which the double thickness edge portions provide spacing between adjacent wraps of fin material.

Referring now to FIG. 1, there is shown a machine for forming and helically'wrapping a finned strip onto a tubular member which is advanced through the machine. The machine is supported on a base or bench 2 which carries the machine for rotation about a substantially vertical axis. A suitable supply of tubular material 3 is fed substantially vertically in the upward direction through the machine. Mounted within the base 2 of the machine is a tube feeding and swaging assembly 4 which provides means for reducing the circumference of the tubing as well as for driving the tubing upwardly through the remaining components of the machine. Arranged on the top plate 6 of the base 2 is a supporting member 7 which supports a rotatable drum 8 for rotation about a substantially vertical axis. The upper end of the rotatable drum carries a rotatable wrapping head generally designated 9 which in turn carries means for supporting a coil of sheet stock as well as fin slitting, forming and wrapping mechanism As may be seen in FIG. 1, the rotatable drum 8 is supported witmn the vertical support '7 by means of antifrictionbearings 11 which permit rotation of the drum. Means are provided for rotating the drum 8 and the head 9, carried by the drum. These means include the drive motor 12 which, through a belt or chain 13 supplies power to a main drive shaft 14. The shaft 14 extends downwardly into a gear box 15 formed in the bottom of the supporting member 7. Attached to the shaft 14 is a large driving gear 16 which meshes with gear 17 aifixed to the bottom of the rotatable drum 8 for rotating the drum and the head 9.

Again referring to FIG. 1, there is shown a second tubular member 18, supported within the rotatable drum 8, and rotatable with respect to the rotatable drum 8. For purposes of clarity in the following specification and claims, this tubular member will be referred to as the rotatable spindle 13. As may be seen in FIG. 1, the rotatable spindle 18 is supported at its upper end within the drum 8 and in an axial passage 11) formed in the Wrapping head 9 by anti-friction bearings 19, and at its lower end by a thrust bearing 20 mounted in the upper plate 6. Thus, the spindle 18 is completely free from the drum 8 and is adapted for rotation independently therefrom. Referring to both FIGS. 1 and '4, the spindle 18 has affixed to its lower end a gear 22 which meshes with a gear 23 or" a gear train also including the gears 24, 25 and 26. The gear train and therefore the spindle 18 are driven by the drive shaft 14- through a gear 27 positioned on the shaft below the gear 16. Through this gear train, rotation is imparted to the spindle 18 in same direction as the rotational motion applied to the rotatable drum 3. Inasmuch as both the rotatable spindle 18 and the rotatable drum 8 are driven by gearing means deriving their power from the common shaft 14, both of these means are driven in timed relation with each other. However, for purposes to be explained later on in the specification, the rotatable drum 8 is geared to rotate at a rotational velocity slightly faster than that of the rotatable spindle 18.

A tubular guide 28 is disposed centrall within the spindle 18 and arranged to receive the tube 3 from the feed roll assembly 4 during operation of the machine. The tubular guide 28 is rigidly supported at its lower end by a supporting strut 29 extending from the housing of the feed roll assembly 4, and vertically supported at its upper end by an anti-frictional bearing 31 (best seen in FIG. journalled in the rotatable spindle 18. The tubular guide 28 is rigidly supported and extends upwardly through the rotatable spindle into a turret 32 carried on the rotatable head 9. On the end of the tubular guide within the turret 32 there is provided a wrapping member 33 through which the tubing 3 is advanced while fin material is helically wrapped onto the tubing 3 as the head 9 is rotated about the tubing.

Referring again to FIG. 1, in order to drive the tube feeding and swaging assembly 4 for advancing the tubing 3 upwardly through the machine, the shaft 14a extends downwardly through the upper plate 6 into a gear box 34 positioned on the top of the housing carrying the tube swaging and feeding assembly 4. Gearing means (not shown) in the gear box drive a worm shaft 36 having a plurality of worms 3'7 thereon, each meshing with gearing means on the swaging and feeding roils for driving the three sets of rolls provided in the illustrated machine. Tubing 3, after it has been sized in the swaging and tube feeding assembly 4 is advanced upwardly into the tubular guide 28 as shown in FIG; 1. This carries the tubing 3 upwardly through the guide 28 where it enters the turret 32 through an opening in the top of the wrapping member 33. The tube feed and swaging assembly is clearly described in my aforementioned patent application SN. 763,5 l4 and a more detailed description of'this tube driving and swaging means isvnot deemed necessary in the amount of tubing of a precise'dimension' through the wrapping member 33 for each revolution of the wrapping head.

As may-best be seen in FIGS. 1 and 2, a coil supporting means or coil supporting table 42 is provided on the rotatable head for carrying a large coil of strip stock around the periphery of the rotatable head 9. The table 42 is mounted around the periphery of the rotatable head 9 and is so mounted that it is free to rotate with respect to the head. More specifically, the supporting table 42 rests on the shoulder 43 around the periphery of the rotatable head 9 and is slideable thereon. A coil 41 of strip stock is positioned on the table and is clamped at its outer diameter so that for all practical purposes there is no slippage between the coil and the table. As may be seen in FIG. 2, strip stock 41 pays off from the inner diameter of the coil and passes around an idler roll 44 where it is guided into the turret 32. As will be explained later on in the specification, strip stock is removed from the coil 4-1 and pulled into the turret 32 by a slitting means which comprises a pair of lancing rolls 56 and 57. The lancing rolls alwaysacquire the same amount of strip material for each revolution of the head.

in order to feed strip material from the inner diameter of the coil 41, it is necessary to rotate the table 42 around the wrapping head 9 at the same time that the wrapping head 9 is rotating around the tubing. As wasmentioned previously, the head 9, which is mounted on the drum 8, is rotated in the clockwise direction (as seen in FIG. 3) slightly faster than the spindle 18, and the head 9, therefore, advances around the spindle 18 a predetermined amount for each revolution of the head.

Referring to FIG. 3, it can be seen that the spindle 18 is provided with a gear means 46, which for ease of explanation should be considered a sun gear and will be hereinafter referred to as such, although the spindle 18 is also rotated in the clockwise direction. Because the head 9 is also rotated in the. clockwise direction, but slightly faster than the spindle 18, the planetary gear 47, which engages with the sun gear 4-6 on the spindle, is actually progressed around the sun gear 46. Thus gear 47 is 1'0- tated in the clockwise direction with respect to its mounting axis or shaft 39 during rotation of the wrapping head 5". Shaft 39 also carries the gear 48 which engages with the idler gear 49 on the shaft 55 also journalled in the wrapping head 9 and drives gear 49 in the counterclockwise direction with respect to the shaft 55. As may be seen in FIGS. 3 and 7, shaft 55 also carries the small gear 50 which engages the large drive gear 51 and rotates this gear in the clockwise direction. Drive'gear 51 engages with a ring gear 52 mounted on the inner diameter of the supporting table 42 and progresses the table 42 around the head 9 in the clockwise direction as seen in FIG. 3, during rotation of the head in this same direction. Thus, for each revolution of the head 9, the table 42 is advanced a predetermined distance around the head 9 and strip material 41 is paid off from the head;

Returning now to FIG. 2, the strip stock 4-1 is pulled from the inner diameter of the coil into the turret 32 by the slitting rolls 56 and 57 and passes through an aperture in the turret having mounted therein an idler roll 44. The strip stock 41, as will be hereinafter explained, is formed within the turret into a finned member which is wrapped onto the tubing 3 being advanced upwardly through the turret. The strip stock 41 passes through a pair of guide rolls 53 and 54 which direct the stock into the slitting means which slits the strip material at intervals a plurality of slender fin sections each connecting with a base section extending the length of the strip material. In the preferred embodiment of the invention, the slitting means comprises the aforementioned pair of slitting rolls 5d and 57 which, as may be seen in FIG. 7, are tanden slit.-

ting rolls including upper and lower slitting units separated by a short open space 60. The slitting rolls slit the fin stock 41 at equal intervals from the outer edges thereof toward the center of the material, whichpasses through the open space between the respective cutting edges of the tandem rolls 5i; and 57. Thus the material passing through the slitting rolls es and 57 is slit into the form shown in FIG. 11 with a plurality of longitudinal fin sections 58 being formed on either side of the central.

or base section 5? which passes through the center portion of the slitting rolls and, thus, is not serrated.

In order to rotate the slitting rolls, there is provided in the rotatable head 9 a gearing means or gear chain which derives its rotational power from the sun gear 46 as the rotatable head 9 advances around the rotatable spindle 18. Referring now to FIGS. 3 and 7, it can be seen that the shaft 61 which is attached to the slitting roll 56 extends downwardly into the rotatable head and has afiixed to the bottom thereof a gear 62. Gear 62 meshes with gear 49 which is, in turn, driven by the gear 48 (seen in FIG. 3) attached to the same shaft as the planetary gear i7. Thus, as the planetary gear 47 is advanced around the sun gear 46 on the spindle, it imparts rotational motion to the slitting rolls 56 and 57 through the gear train journalled in the wrapping head 9. As the strip stock passes through the slitting rolls the cutting teeth of the slitting roll 56 displaces the fin stock thereby serrating the fin stock and, by this action, also drives the slitting roll 57 through the fin stock. In other words, as may best be understood by reference to the FIG. 10, the meshing of the slitting teeth of the two slitting rolls 56 and 57 respectively causes the roll 57 to be driven through the material by the slitting roll 56.

It should be mentioned in passing that each fin section 58 is canted at an angle with respect to the original plane of the strip stock ll as the strip passes through the slitting rolls. it has been found that these canted fin sections are not asdesirable in the finished heat exchange tubing as sections which are arranged to present less resistance to air flow. Moreover, these canted fin section make the wrapping of the fin material somewhat difficult in that they It should be noted that the backing roll 64 is not powered by any positive driving means and rotates because of the frictional force resulting when it forces the strip stock into the groove of the roll 66. After the strip stock is formed into a substantially U- shaped cross section by the forming rolls 64 and as, it is directed into a hem forming means, shown best in FIGS. 8 and 9, for crimping or folding the narrow portions 5% of the base section downwardly upon the remaining portion of the base section toform double thickness edge portions 59!) on each side of the finned strip. The hem forming means in the present invention, comprises a plurality of forming rolls including a roll 69 having a groove 70 around the peripheral edge thereof. The groove 7t) in the roll 69 is a width just large enough to receive the width of the base section of the U-shaped cross section of the strip stock. The base section of the U-shaped strip material enters the groove 70 of the roll 69 and is confined therein by a backing roll 71 and a pair of diagonally disposed hemming rolls 72 and 73'. The hennning rolls 72 and 73 and the rolls 69 and 71 all have their axes in a single vertical plane (as seen in FIG. 8) with the roll 69 meeting the hemming rolls 72 and 73 to bend the edge portions 59a on opposite sides of the. base section downwardly upon the remaining portion of the base section 59 as the rolls meet in substantially common line of tangency, as shown in the larger diagram of FIG. 9. Each of the rolls 72 and 73, which approach the roll 69 diagonally, are provided with forming surfaces 74 and 76, disposed at an angle with respect to each other, which entend to' hang up on each other and various components of the machine. Therefore, means, which will be described in greater detail later on in the specification, are provided for straightening the individual fin sections with respect to the plane of the remaining fin sections.

Referring to FIG. 2 it can be seen that, as the strip material leaves the slitting means, it is directed by "a guide 63 into a forming means comprising a pair of forming rolls 64 and ea. As may be seenin FIGS. 5 and 6, the forming roll 66 is provided with a groove around the peripheral edge thereof into which the backing roll 64 extends. The backing roll 64 is journalled into the rotatable head 9 while the grooved roll as is attached to the upper end of the rotatable spindle 18. While, the roll 66 is rotated by the spindle 13,-the roll 64 is carried by the rotatable wrapping head 9 around the roll as during rotation of the head 9 around the rotatable spindle l8. Thus, although both the spindle l8 and thereby the roll 66 are rotated in the clockwise direction, the fin material is passed etween the forming rolls 6% and 66 because the backing roll 64 moves in a planetar type or" motionin the clockwise direction (as seen in FIG. 2) around the grooved roll 66. As the fin material passes between the rolls 64 and 65, the individual fin sections 58, and narrow portions. 59a of the base section on both sides of the base section 59 are bent at approximately a 90 angle with respect to the rema ning portions of the base section 59.

This may best be seenby referring to the enlarged view of the'forming rolls shown in FIG. 6. Thus, the forming rolls cooperate to provide a U-shaped or channel-shaped base section and confine or crimp these portions between the base section 59 and opposite sides of the backingroll 71. This provides a continual trend or force against the narrow portions 5% of the base section as the U-shaped strip is advanced through the hemrning rolls and causes those portions 59a to bend ove'r upon the remaining portoward each other as the base section 59 is folded into material emerges from between the two forming rolls a; r

l and 66, it takes on a substantially U-shaped cross. section] tion of the base section 59 while, at the same time, the fin sections 58 are retained outwardly from the base section at substantially a perpendicular angle therefrom.

As was previously mentioned, the slender fin sections 58 are canted at an angle with respect to the original plane of the strip stock as they are serrated in the slitting rolls 56 and 57. As may be seen in FIG. 9, the fin sections 58 are confined against the opposite surfaces of the backing roll 71 and the surfaces 76 of each of the rolls 73 and 72. This provides a means for straightening the individual fin sections with respect to the plane of the remaining fin sections. As the fin sections are each successively passed between the surfaces 76 of the diagonal hen-iming rolls and the backing roll 71, the cant in each joilrnalled in the rotatable head 9, which also engages] with the sun gear as on the spindle 1 .8. This gear 77 is also a planetary gear and, similarly to the gear 47, also slowly advances around the gear 46 as the head 9 rotates around the spindle '18. As the head 9 rotates around the spindle 18 and the gear'77rotates around the sun gear 46, rotational motion is imparted to the planetary gear 77 which motionis transmitted to a gear 7&also journailed in the head 9. Gear 7 8 drives the shaft 79 attached to the grooved roll 69. On the upper end ofthe shaft '79- is' a bevel gear 81 meshing with -a bevel gear 82 {attached to ashaft which drives, the diagonal roll 72 in the opposite rotational direction than the direction that the roll 69 is rotated. Similarly on the lower portion moving in the same direction at their point of common tangency with the fin strip as it is passed therethrough.

Referring again to FIGS. 2 and 3, the finned strip of a stock follows a short distance around the grooved roll 69 and is directed onto a turn-around roll 8%. The roll 89 is mounted at a slight angle with respect to the head 9 and causes the finned strip to be directed slightly upward with respect to the head 9 so that itis wrapped onto the tubing 3 being advanced through. the head. Thus, the fin strip approaches the tubing 3 at the angle required for helically wrapping the strip onto the tubing as the tubing is advanced through the Wrapping member 33. This wrapping member 33 is attached to the tubular guide 28 extending upwardly through the spindle 18. Below the wrapping member 33 the grooved roll 66 is rotating at a fairly substantial rotational velocity. However, the wrapping member 33 is stationary, as is the tubular guide 28, and provides a wrapping surface upon which the material is wrapped onto the tubular member 3 being advanced upwardly through the tubular guide 28.

The strip of fin material is wrapped onto the tubing 3 with the base section 59 in flatwise engagement with the surface of the tubing and with the fin sections 59 projecting outwardly from the tubing. As the strip is wrapped the fin sections 58 spread apart toward their outer ends leaving a pie-shaped opening between adjacent fin sections thereby breaking up the continuity of the helical fin structure around the tubing. In the preferred embodiment of the invention, as seen in FIG. 12, the double thickness edge portions 5% on opposite sides of the base section of the adjacent wraps of the strip are placed in abutting relationship. The double thickness edge portions 5% serve to space the outwardly extending fin sections of one" wrap from the outwardly extending tubing 3 a length of fin material slightly greater than the circumference of the tubing 3 as determined by the helical wrapping angle. Thus, for eachrevolution of the head 9, approximately this length of fin stock must be paid off the inner circumference of'the coil 51 and passed through the slitting rolls and fin forming rolls. It will be understood therefore that this length of fin material, wrapped for each. revolution, governs the rotational speed at which the slitting rolls 56 and 57 and the hemming rolls 69, 71, '12 and 73 are rotated. Furthermore, this length of fin material to, be wrapped onto the-tubing governs the velocity at which the forming roll 64 is to be rotated around the grooved roll 66 to. form the strip stock into a substantially U-sh'aped cross section. That is, the length of fin stock formed into a substantially, U-shaped cross section' is determined by the velocity at which the backing roll 64 rotates around the grooved roll 66 (considering a head 9 (or drum 8) and the spindleldwhich'determines the length of fin stock ,formedby these; rolls. it can be seen, therefore,v that once the .lengthof fin stock to be Wrapped onto the tubing for eachrevolution is determined, then the difierence in rotational velocity. between the head 9 (or drum 8) and spindle 155 is necessarilyfixed anda proper geari ratio must be obtained to provide this.

bers. This proper gear ratio is provided in the gear box 16 which promotes the requisite diiierencein rotational 1 velocity between the drum 8 and the spindle 18 through the gear trains which drive these members from the common drive shaft 14.

When the difference in rotational velocities between the spindle 18 and drum 8 (or head) is small then the length of fin stock formed by the fin forming and slitting components is small. And conversely, when the diiference in rotational velocities between the spindle 18 and drum 8 (or head) is greater, then the slitting and forming components on the head are operated at a greater speed to form relatively more fin material for each revolution of the head. Thus, it is only necessary to change the gear ratios (in the gear box 15) afiecting the rotational velocity of the drum 8 and the spindle 18, thereby, changing the difference in rotational velocity between these members,'to accomplish a change in the amount of fin material formed for each revolution of the head. This is very advantageous when changing over from one size tubing 3 to another which, of course, necessitates a change in the length of fin material to be wrapped for each revolution of the wrapping head 9.

Referring now to FIGS. 1 and 2, it would appear that there are two coils 41a and 41b of strip stock on the support table 42. Actually this is one continuous coil of strip stock which has gradually separated so that the inner portion 41b thereof is built up around the turret 32. The separation of the coil of strip stock 41 is caused by the fact that the coil supporting table'42 is always advanced the same amount, or'an equal rotational angle, around the head for each revolution of the head while the linear length of strip stock payed off by a new coil when first placed on the table is less than that demanded by the fin slitting, forming and wrapping components. It, of course, is understood that the inner diameter ofa coil of strip stock of material is necessarily much smaller than the outer diameter of the coil and that, for all of the radii of the coil from the inner diameter of the coil to the outer diameter, the length or" strip stock advanced for each revolution of the head must necessarily vary over a wide range. Therefore, the linear length of strip stock payed olf from the coil will necessarily be less for each revolution of the head when the coil of strip stock is first placed on the table and the radius from the axis of rotation to the inner diameter of the coil is relatively smaller than when most of the'coil has been used and the pay off point from the inner diameter of the coil is consequently at a greater radius from the center of the machine.

The machine of the present invention is designed so that the length of strip stock required by the components in the turret 32 is greater than that payed oh by a new coil having a relatively small inner diameter. This means that, for each revolution of the head, the wrapping components require a small increment more fin stock than is i I supplied by the advancement of the coil around the head.

This causes thepay oii point 90 on the new coil to gradually progress counterclockwise (as seen in FIG. 2)

around the coil so that the strip stock wraps itself around each revolution of the wrapping head 9. When this point.

is reached' the build up of coil 41b around the turret ceases and the inner coil 41b beginsto-gradually diminish.

' it should be mentioned that, as the inner radius of the 'difierence inrotational velocity between these two mem:

coil 41a gets even larger, the linear length of stock advanced by the table, for each revolution of the head, be

comes greater than thatfrequired by thecomponents in the turret. This causes the pa off point 93 to reverse and to progress in the opposite or clockwise direction aroundthe coil As-the pay off point 96) moves in fthe clockwise directiomthereis a gradual reductionin the build up of coil 415 as well as a reduction in the outer coil 41a. Thus, as is illustrated in PEG. 1, the coil I I 415 of strip stock builds up around the outer periphery of the headfor the first portion of wrapping of each new coil of strip stock. This b ild up must be kept to a reasonable amount so that the friction developed by the material as it is pulled into the turret for forming operation does not create too great a force and thus cause the material to break or tear. A plurality of rollers 92 have been mounted at spaced intervals around the outer periphery of the turret upon which the inner coil 41b of strip material rides to reduce the friction as much as possible. The rollers prevent the inner coil 41b from binding around the turret 32 and aid the uniform pay off from the inner diameter or" the inner coil 41!). As stated previously, when the inner radius or pay-off point 9t? on the coil 41a from which the strip material is taken, reaches that point wherein the advancement of the coil at that particular radius equals the linear length of strip stock acquired for each revolution of the head by the slitting rolls 55 and 57, then the amount of build-up around the periphery of the turret begins to diminish. The machine of the present invention is designed so that, when the build up around the outer periphery of the turret 32, or

the coil 41b, is completely eliminated, there is no longer any strip stock left in the outer coil diet, so that there is no chance of overrunning the point of entry or idler roll 44 in the turret. However, overrurning the point of entry or idler roll 44 is not too critical a factor inasmuch as the material is merely fed from the opposite direction into the entry and one or" the small rollers 92 acts as an idler roll to reduce friction at the point of entry.

As mentioned in my previous application, an adhesive bonding material is directed onto the tubing 3 in the area just prior to its Winding point with the fin material. This is provided by an adhesive bond which is directed onto the tubing in the tubular guide at some point just ahead of the wrapping member 33. in the illustrated embodiment of the invention, this adhesive applicating means is not illustrated although it is shown and claimed in the previous application.

The machine of the present invention uses a new and improved method for manufacturing a finned heat exchange tube of this type. The new method includes as its first step the slitting of a strip of sheet stock inwardly from opposite edges thereof toward the center at spaced intervals to provide a plurality of slender fin members each connecting with an unslit center or base section extending the length of the strip. This step is performed by theslitting rolls 56 and 57 (best seen in FIG. 7) on the wrapping head 9 which slit the strip stock into the form shown in FIG. 11 with the slender fin sections 53 extending outwardly from the unserrated central base section 59 that extends the length of the strip of stock. The base section is then folded into a substantially U- shaped cross section with narrow portions 59a of the base section and the connecting fin members 58 being folded at approximately 90 with respectto the remaining portions of the base section 5%. This U-shaped cross section is formed by the forming rolls 6d and as (shown in PlGS. 5 and 6) as the fin stock is advanced through these rolls with the backing roll 64 engaging the unslit base sec tion 59 of the slit fin stool: and forcing it into the groove 7% in the roll 66. After the fin stock is formed into a U-shaped cross section it is passed through a hemming means inwhich the narrow portions 59:: or" the base section are folded over onto the remaining portions of the base section to form double thicltness edges 5% on opposite sides of the base section While the slender fin members are retained in their outwardly extending position. This step is performed in the hemming means. on themachine comprisingthe rolls 69, 71, 72 and 73.(shown' best in FIGS. 8 and 9). As previously explained, the upwardly extending portions59'a of the base section are folded over onto the remainingportion of the base section 59 to form double thickness edge portions 5912 while the fin sections 53 are retained in their outwardly extending position from the base section by the coopera- 1% tion of the backing roll 71 and the two hemming rolls 72 and 73.

In the preferred embodiment of the invention, the narrow upwardly extending portions 5% of the base section "5t which form part of a U-shaped cross section are of a width substantially /6 of the total width of the base sec tion shown inFIG. 11. Thus, when these portions 594 are folded over to form the double thickness edge portions of the fin strip, they form a double thickness edge portion of a width approximately A that of the remaining base section. The finned strip is then wound onto the surface of a tubular member with the base section in flatwise engagement with the surface of the tubular member and with the slender fin sections extending radially outward therefrom.

As best seen in FIG. 12, the double thickness edge portions 5% are the width of the remaining base section 59 and provide a spacing means for spacing the adjacent wraps of helically wound fin material on the tubing. The double thickness edge portions 5% of two adjacent wraps space the adjacent rows of fin sections 58a and 58b a distance apart substantially equal to the distance that the rows of fin sections 58a and 58c are apart on a single wrap of finned material. Thus all of the rows of fin sections are spaced apart equal distances in the finished tubular structure.

In the past, it has been a very difficult opera-tion to form a finned surface structure with a serrated type fin member because the fin stock would not permit too great a wrapping tension before it would sever or break. By the present method, the base section of the fin member is formed into a substantially stronger structure prior to the fore, increasing the overall wrapping efficiency. That is,

by the present method it is possible to wrap two rows of finned sections simultaneously thereby doubling the Wrap ping speed. 7

While in accordance with the patent statutes there has been described what is at the present considered to be the preferredembodimcnt of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, the aim of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A machine for forming and helically wrapping a strip of fin material onto a tubular member comprising a base, a rotatable head supported by said base for rotation about a substantially vertical axis, said rotatable head hav,

ing an axially disposed passage therein, means for rotatmg said head, an annular coil supporting table mounted around the periphery of said head for supporting a coil as the rotation'of said head and. ata rotational velocity diifering from that of said rotatable head, a gear train on said head adapted'to engage with and drive said annular coil supporting table a predetermined distance'around said rotatable head for each revolution of said head sothat' strip stock is uniformly fed from the inner diameter of said coil during rotation of said coil around said head,

. gear means on saidspindle engaging said gear train on ceiving strip stock from the inner diameter of said coil and forming said; strip stock into fin material having a l 1 base section and at least one angularly disposed fin section, means on said head also engaging said gear means on said spindle for driving said fin forming means in timed relation with the rotation of said head mound said spindle, and means on said head for directing said fin material onto said tubing being advanced through said head with the base section of said material disposed in fiatwise engagement on said tubing and with said fin section extending outwardly therefrom thereby wrapping said fin material onto said tubing as said head is rotated around said tubing.

2. A machine for forming and helically wrapping a strip of finned material onto a tubular member comprising a base, a rotatable wrapping head supported by said base for rotation about a substantially vertical axis, said rotatable wrapping head having an axially disposedpassage therein, means for rotating said head, an annular coil supporting table mounted around the periphery of said head for supporting a coil of strip stock around said head, said annular table being rotatably mounted on said head, a ring gear disposed around the inner radius of said coil supporting table, a hollow spindle extending into said axial passage in said head and supported by said base and said head for rotation independently of said head, said spindle having a sun gear around the outer circumference thereof in said axial passage, means for rotating said spindle in timed relation with the rotation of said headand at a rotational velocity difiering from that of said rotatable head, a gear train on said head including a planetary gear engaging'with said sun gear on said spindle, said gear train engaging said ring gear of said annular coil supporting table for rotating said table around said rota-table head a predetermined distance for each revolution of said head so that strip material is uniformly fed'from the inner diameter of said coil during rotation of said coil around said rotatable head, means for advancing tubing at a governed rate through said hollow spindle into said axial passage in said rotatable head, forming rolls on said head for receiving strip stock from the inner diameter of said coil and forming said strip stock into fin material having a base section and at least one angularly disposed fin section, a second gear means on, said head also engaging with saidsun gear of said spindle for driving said fin forming means in timed relation with the rotation of said head, and means on said head for directing said fin material onto said tubing being advanced through said head with said base section of said fin material disposed in flatwise engagement on said tubing and with said fin section extending outwardly therefrom thereby wrapping said fin material onto said tubing as said head is rotated around said tubing.

3. A machine for forming and helically wrapping a strip of fin material onto a tubular member comprising -a base, a rotatable head supported by said base for rota tion about a substantially vertical axis, said rotatable head having an axially disposed passage therein, means for v rotating said head, an annular coil supporting table passage, means, for rotating saidis'pindle in timed rela-v tion with rotation of said head and at a rotationalveloeity differing from that of said rotatable head, a gear train on said head including a planetary gear engaging witll'said sun gear on said spindle, said gear tr'ainfengaging with saidringgear on said annular coil supporting table for rotating said table a predetermined distance around said rotatable head 'for each revolution of said head so that strip material is uniformly fed fromthe inner diameter of said coil during rotation of said coil around said head,

slitting rolls mounted on said head into which said strip stock is fed, said sitting rolls slitting said strip stock inwardly from its outer edges toward its center at spaced intervals to provide a plurality of slender fin members each connecting with a base section extending the length of said strip, gear means on said head also engaging said sun gear on said spindle for driving said slitting rolls in timed relation with the rotation of said head, means for forming said strip of fin material into a substantially U-shaped cross section including a forming roll on the end of said spindle extending into said axial passage in said head, said forming roll having a groove around the periphery thereof, a mating roll mounted on said head with the peripheral edge thereof extending into said groove of said forming roll for forcing said base section of said strip stock into said groove of said forming roll so that the sides of said groove cause said slender fin members and a narrow portion of said base section on each side thereof to fold at approximately right angles to said base section, hemming means on said head for bending said narrow portions of said base section over upon said remaining portions of said base section, gear means on said head also engaging said sun gear of said spindle for driving said hemming means in timed relation with the rotation of said head, means for advancing tubing at a governed rate through said hollow spindle into said axial passage in said rotatable head, and means on said head for directing said fin material onto said tubing being advanced through said head with said base flange of said fin material disposed in fiatwise engagement uponsaid tubing and with said edge portionsof said fin material arranged .closely adjacent each other as said head is rotated around said tubing.

4. A machine for forming and helically wrapping a strip of fin material onto a tubular member comprising a base, a rotatable wrapping head supported by said base for rotation about a vertical axis, said rotatable wrapping head having an axially disposed passage therein, means for rotating said head, a hollow spindle extending into said axial passage in said head and supported by said-base and said head for rotation independently of said head, said spindle having a sun gear around the outer circumference thereof in said axial passage, means for rotating said spindle in timed relation with the rotation of said head in the same direction as said head and at a rotational velocity less than that of said rotatable head, means for advancing tubing at a governed rate through said hollow spindle into said axial passage in said rotatable head, an annular turret axially mounted on said rotatable head for rotation therewith, fin'forming and wrapping means mounted in said turret for forming strip stock into a fin material and wrapping said stock onto said tubing being advanced through said axial passage in said head, an annular coil supporting table mounted around the periphery of said head outwardly ofsaid annular turret for supporting a coil of strip stock around said head, said annular table being rotatably mounted'on said head, a ring gear disposed around the inner radius of said coil supporting table, gear means on said .head including a planetary gear engaging with said sun gear on said spindle and a driving gear engaging with said ring gear on said annular coil supporting table for rotating said table around said rotatable head a predetermineddistance for each revolution of said head so that strip material is uniformly fed from the inner diameter of said coil during rotation'of'said coil around said rotatable head, means for driving said fin forming means in timed relation with the rotation of said rotatablehad so that fin stock isuniformly consumed by said forming means for eachvrevolution of said head, and a plurality of rollers freely mounted at-spaced intervals around the periphery of 'saidturret said rollers preventing fin stock from binding around said turret asjsaid fin stock is fed.

5. A machine for forming and helically wrapping a A strip of fin material onto a tubular member comprising a base, a rotatable wrapping head supported by said base for rotation about a substantially vertical axis, said rotatable Wrapping head h "ing an axially disposed passage therein, means for rotating said head, an annular coil supporting table mounted around the periphery of said head for supporting a coil of strip stock around said head, said annular table being rotatably mounted on said head, a hollow spindle extending into said axial passage in said head and supported by said base in said head for rotation independently of said head, means for rotating said spindle in the timed relation with the rotation of said head in the same direction as said head and at a rotational velocity less than that of said rotatable head, means mounted on said head operated in timed relation with the rotation of said head around said spindle for driving said annular coil supporting table around said head a predetermined distance for each revolution of said head so that strip material is uniformly fed from the inner diameter of said coil during rotation of said coil around said head, means for advancing tubing at a governed rate through said hollow spindle into said axial passage in said rotatable head, an annular turret axially mounted on said rotatable head for rotation therewith, an aperture in said turret through which fin stock being fed from said coil on said support table is directed into said turret, fin forming and wrapping means mounted in said turret for forming said strip stock into a fin material and wrapping said material onto said tubing being advanced through said axial passage in said head, means for driving said fin forming means in timed relation with the rotation of said rotatable head so that fin stock is uniformly consumed by said forming means for each revolution of said head, and a plurality of rollers freely mounted at spaced intervals around the periphery of said turret, said rollers preventing fin stock from binding around said turret as said fin stock is fed from the inner. diameter of said coil and consumed by said fin forming means within aid turret during rotation of said head.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A MACHINE FOR FORMING AN HELICALLY WRAPPING A STRIP OF FIN MATERIAL ONTO A TUBULAR WRAPPING A BASE, A ROTATABLE HEAD SUPPORTED BY SAID BASE FOR ROTATION ABOUT A SUBSTANTIALLY VERTICAL AXIS, SAID ROTATABLE HEAD HAVING AN AXIALLY DISPOSED PASSAGE THEREIN, MEANS FOR ROTATING SAID HEAD, AN ANNULAR COIL SUPPORTING TABLE MOUNTED AROUND THE PERIPHERY OF SAID HEAD FOR SUPPORTING A COIL OF STRIP STOCK AROUND SAID HEAD, SAID ANNULAR TABLE BEING ROTATABLY MOUNTED ON SAID HEAD, A HOLLOW SPINDLE EXTENDING INTO SAID AXIAL PASSAGE IN SAID HEAD AND AND SUPPORTED BY SAID BASE AND SAID HEAD FOR ROTATION INDEPENDENTLY OF SAID HEAD, MEANS FOR ROTATING SAID SPINDLE IN TIMED RELATION WITH THE ROTATIONOF SAID HEAD IN THE SAME DIRECTION AS THE ROTATION OF SAID HEAD AND AT A ROTATIONAL VELOCITY DIFFERING FROM THAT OF SAID ROTATABLE HEAD, A GEAR TRAIN ON SAID HEAD ADAPTED TO ENGAGE WITH AND DRIVE SAID ANNULAR COIL SUPPORTING TABLE A PREDETERMINED DISTANCE AROUND SAID ROTATABLE HEAD FOR EACH REVOLUTION OF SAID HEAD SO THAT STRIP STOCK IS UNIFORMLY FED FROM THE INNER DIAMETER OF SAID COIL DURING ROTATION OF SAID COIL AROUND SAID HEAD, GEAR MEANS ON SAID SPINDLE ENGAGING SAID GEAR TRAIN ON SAID HEAD FOR DRIVING SAID GEAR TRAIN AS SAID HEAD ADVANCES AROUND SAID SPINDLE, FORMING MEANS ON SAID HEAD FOR RECEIVING STRIP STOCK FROM THE INNER DIAMETER OF SAID COIL AND FORMING SAID STRIP STOCK INTO FIN MATERIAL HAVING A BASE SECTION AND AT LEAST ONE ANGULARLY DISPOSED FIN SEC- 